High-frequency inductance



Sept. 28*, 1 92s.

' 1,601,400 M. LATOUR HIGH FREQUENCY INDUCTANCE Filed July 15, 1920 4 [lllllllllll flies-W70? Pm aase t. 2a, 1926.

UNITE STATES PATENT OFF ICE.

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LATOUB, OI PARIS,- I'RANCE, ABSIGNOR TO LATOUR CORPORATION, 01. JERSEY CITY, NEW JERSEY, CORPORATION OF DELAWARE.

HIGH-FREQUEN CY INDUCTANCE.

Application filed July 15, 1920, Serial No. 896,508, and in France December 18,

(GRANTED man rim raovrsrous or THE m or mean a, 1921, 41 cur. 1., ms.)

The present invention relates to wireless systems ofcommumcation 1n WhlCh the amplitude of the high frequency current trav-- ersing the antenna is modulated in accordance with an audible frequency. The object of the invention is to provide a special coil which is inserted in one of the high frequency current circuits and the self induction of which is varied in accordance with the fluctuations of the modulating frequency.

In accordance with a well known method of controlling at will an alternating current without interrupting the circuit of this current, a coil is used which is provided with two windings of a single magnetic circuit. One of the two windings is traversed by the alternating current to be regulated, and the other by the continuous current. By suit-f ably varying the intensity of the continuous current, the self inductance of the coil in said arrangement may be varied as far as the alternating current is concerned and in this manner the amplitude of; the alternating current may be regulated.

It is well known that this effect of saturating the core may be obtained by using instead of the continuous current, an alternating current of lower frequency than that of the current to-be regulated.

' Irrespective of the methods used in the general alternating current art, the present invention provides in a wireless continuous wave transmitter, an arrangement for modulating the amplitude of the high frequenc currents of the antenna in accordance with an audible frequency by varying the value of an inductance inserted in the antenna.

In wireless telegraph this inductance cannot be readily contro led by means of a simple alternating current in the manner suggested in an allied branch of the electrical art (U. S. Patent 1,337,875) because the modulation obtained is not suflicient.

In accordance with the present invention,

I employ a coil, one of the windings of which be high fre uency antenna I is traversed by t current, the saturating effect eing obtained by the combined electro-magnetic action of a direct current and an alternating current, the fluxes of which are superimposed in the iron of the magnetic circuit. K

carry the coils 2 and 4 and also by the alternating current Computations and experiments show that under, these conditions considerable modulating effect may be obtained and the output of modulated high frequency waves is excellent.

As a matter of fact, if we assume that the high frequency current is modulated simply by means of a low frequency current, the

following'equation will be obtained for the modulated antenna current any modulation.

7 being the sending frequency.

a::21rf' 'Im=I sin rut (sin at) f being the modulating frequency.

On the other hand if a direct current superimposed ont-he alternating current of the same amplitude is used for the modulation, then we will have I Im=1sin wt (1-sin at) It will be seen that the function (1) varies between zero and 1, whereas, the function (2) varies between zero and 2, which proves that the second method of modulating gives better results than the first method.

The object of the present invention is illustrated in the enclosed drawing in which:

1 is a magnetic core having three branches provided with two windings. The middle branch carries the winding 6 traversed by the antenna current.

a manner to form a single winding traversed by the direct current flowing from the source enerated by the generator 8, e. g., through the agency of a transformer 7. In the drawings the lateral. branches are shown as having large cross sections because due to a construction of this tyge the high frequency energy losses are re uced by reducing the high fre uency induction in these branches. Pr'eferab y, the coil 6 is arranged in such The side branches 3 interconnected in a manner that it presents the least possible core and coupled to the controlled circuit and another winding arranged to be energized by direct currents and alternating currents of audible frequency, said last men tioned winding being mounted-in co-operative relationship with the lateral branches of said core.

2. In a regulating device for controlling a signal wave in a controlled circuit, in combination, a magnetic core having three branches, a winding in co-operative relationship with the middle branch of said core arranged to be coupled to the controlled circuit, another winding arranged to be energized by direct currents "and alternating currents of audible frequency, said last mentioned winding being mounted in co-operative relationship to the lateral branches of said core, and meansfor varying the amplitude of the currents traversing said last mentioned winding.

3. In a regulating a signal wave and a controlled circuit, in combination, a metallic core having three branches, a winding arranged in co-operative relationship with the middle branch of said core and arranged to be coupled to the controlled circuit, another winding ardevice for controlling.

ranged to be energized direct currents and alternating currents of audible frequency, said last mentioned winding being mounted in co-operative relationship with the lateral branches of said core, and means for varying the amplitudes of the currents traversing said last mentioned winding.

4. In a device for modulating a signal wave, in combination, a magnetic core member comprising three branches having their corresponding ends connected together, a first winding arranged to be traversed by the signal wave mounted in co-operative re lationship with the middle branch and a controlling winding mounted in co-opera tive relationship with each of the lateral branches of said core and arranged to be traversed by modulating currents, all of said windings being so wound and arranged as to result in substantially zero voltage being induced in the first winding due to the magnetic flux set up by the controlling windings and as to' result in the voltages induced in the controllin windings due to the magnetic flux of the rst winding being substantially 180% out of phase with each other whereby they substantially neutralize.

5. In a magnetic modulator, a core having lower permeability [than iron, and means to apply simultaneously a high frequency field and a signal-varied low frequency field to said core.

6. In a magnetic modulator, a core comprising nickel, and means to apply simultaneously a nigh frequency field and a signal-varied low frequency field to said core.

In witness whereof, I have hereunto signed my name.

MARIUS LATOUR 

